Building commissioning is an inter-disciplinary process that involves evaluating the many moving parts of a proposed building project while it is still in the planning stages. Re-commissioning, which evaluates and tweaks the systems of an existing building, is a similar process. Evaluating HVAC system designs is a large part of building commissioning, as defined in ASHRAE Guideline 1.1-20071. The commissioning process focuses first on macro-level system components like pumps, generators and boilers, before delving into smaller components like ducts and exhaust fans. This is because the placement of the latter is often subject to the placement of the former, which is constrained by architectural design and intended use patterns of the building.
This process can involve communication between separate private contractors, or between property owners and their local governments or zoning boards. Things like occupancy levels or exhaust air specifications can come from the top-down, and impact every facet of a proposed building design. This is even more true when a client is seeking to construct a building that will be marked as environmentally friendly through LEED certification. “The commissioning process must begin early in the design phase of a project for owners seeking LEED certification of their facility. For non-LEED certified buildings, the commissioning process can be limited to the construction phase only.”1 This is due to the high standards that a building must meet in order to attain any of the LEED certification levels; things as rudimentary as the positioning of a building in relation to the region’s solar trajectory patterns can affect both the basic architectural design and the parameters for the HVAC system installed therein.
The end goal of a building commissioning process is to negotiate design parameters such as local climate, building positioning, and budget, with desired client outcomes like ideal temperature, humidity, and air quality levels. This can involve looking outside the scope of the HVAC system itself, to other systems which may interact with it. An example is material choice: the choice of building materials will likely be made based on financial, aesthetic and other priorities. However, the choice of building material will affect the heat absorption rate and ambient temperature of the finished building, so the two designs must work inter-dependently to ensure optimal performance.
It’s important to remember that while good design can pre-empt a whole slew of problems, good maintenance is just as key, building commissioning seeks to ensure that a building functions as expected upon completion, but this does not negate the need for regular maintenance to ensure optimal and intended functioning of HVAC systems. However, a well-designed system is less likely to encounter some of the design flaws that can increase the need for maintenance and part turnover, like overheating.
Building commissioning is a vital service that ensures a smooth transition from drawing to completion of a building project. As the old adage goes: measure twice, cut once.